Process and apparatus for treating paper-pulp



HOWARD.

Patented Nov. 18, 1919.

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INVENTOR W G Cfffowazd T 26 y 18 2/ 1 23 16 BY -Wfi W GUY c. HOWARD, or TACOMA, WASHINGTON.

rnocnss AND APPARATUS FOR. TREATING PAPER-PULP.

-To all whom it may concern:

Be it known'that I, GUY -C. HOWARD, a citizen of the United States, residing at- Tacoma, county of Pierce, and State of Washington, have invented a new and useful Process and Apparatus for Treating Paper-Pulp, of which the following is -a specification.

This invention relates to improvementsin methods and apparatus for treating the fibers of wood .pulp for use in making paper, and particularly to improvements in the operation known as heating the pulp wherein the fiber bundles are brushed, drawn out, and hydrated to improve their quality in paper making. v

The beating of pulp as commonly practised in paper mills is effected in the socalled Hollander or beating engine, and consists in causing the pulp to pass between a rapidly revolving roll and a stationary bed plate and wherein the fibers undergo abrushing out of drawing out,'and hydration. Such brushing or drawing out action is me,- chanical, and consists in a crushing and bursting of the fibers, and, to a certain extent, flattening them.

Hydrating the pulp is a term signifying that the pulp has acquired a soft, greasy or slippery feeling and is supposedly due to the absorption of water by the cellulose fibers. To what extent this absorption, actually takes place and whether it is a mechanical or a semi-chemical absorption of water by the cellulose'fibers, is not definitely known. The chemical natureof cellulose would indicate more or less absorption of water by the fiber and result in its so-called hydration, At the same time, long continued soaking of the fiber in water does not effect the pronounced greasy feel to pulp that results from the beating treatment. The -repeated passage of pulp through a centrifugal pump is, however, reported as Specification of Letters Patent. PatentedfiNov, 18, 1919, Application filed May 8, 1917. Serial N 0. 167,246.

' cylindrical in cross section and many times It is hollow and these fibers are, to an extent, flattened out into what may be described as ribbonshaped fibers rather than cylindrical, and the void inside the fiber eliminated by contact of the opposite fiber wall.

The flattening of pulp fibers in accordance.

with my invention and thereby giving them a somewhat ribbon shape instead of their natural cylindrical shape in cross section, would produce-the slippery, greasy feeling which characterizes long-beaten pulp.

The hydration of the cellulose which gives it a rather more gelatinous structure, is also a factor in giving certain properties to beaten pulp, but it is determined that the resulting shape of the beaten fiber is the most important factor, and that 'to effect a maximum flattening of the fibers with a minimum of actual hydration of the cellulose, improves the paper making quality of the pulp. In this connection, it 1s noted that graphite owes its lubricating properties principally to the thin flake-like shape of its individual particles. Tale is characterized by a cleavage into microscopic plates and has a greasy feeling. Kaolin also occurs somewhat in scale-like crystals and is slippery to the touch, especially when moist.

A fiber that is flat and ribbon-like, is a better paper-making fiber than When cylin I drical in shape as it forms a stronger and better sheet on the paper machine wire, due to both its carrying the free water longer on the wire and the fact that fibers of this shape will mat and interlock more readily by the shake of the wire. It retains the filler and mineral color better and gives a more uniform surface to the sheet. It is also more compact both as regards thickness of the sheet for a given weight and as regards flatness and compactness of surface which is a factor affecting the amount of sizing agent required. It makes a sheet that is easier to dry because in pulp as ordinarily beaten and. treated in the Jordan engine, more or less free water is carried in the internal void space of the fibers and must be evaporated on the driers. F lattening the fibers would eliminate these voids and hence their tendency to carry free water through to the driersa i The question is how this can best be accomplished when dealing with I individual fibers as minute and numerous as encountered in making a sheet of paper. I mon beater with revolving roll and stationary bed plate eifects this flattening aetion to some extent when the roll is down hard and on such fibers as actuall pass between the knife edge on the roll an the-bed plate.

' The long treatment required to thoroughly beat pulp is evidently due to the long time necessary to assure the major portion of the individual fibers actually having passed between the knife edge and the bed plate when account is taken of the fact that some of the fibers are carriedpast the bed plate by the pockets in the roll. 1

Furthermore, if a flattering effect is de- I sired, the rubbingof the knife edge past the stationary bed plate is not thought to be the proper mechanical action to accomplish this although it probably does it to a slight extent. By experiment it is shown that the best flattening efiect will be accomplished by a passing of fibers lengthwise between two solid rolls. If the fibers wereplaced side by side and caused to pass lengthwise in a single fiber thickness between two pressure rolls, the individual fibers would be flattened out into ribbon shapes and the internal voidin each fiber would be eliminated by contact of opposite walls of the fiber.

- If quickly passed through the rolls, this flattening would probably be accompanied by a bursting of the fiber wall at some point to allow the escape of water contained in the The quality of softness and texture of fiber is regulated by the cooking process by which the pulp is made With properly cooked stock, the most efliclent beater would be a machine which gives the maximum flattening and bursting of the individual fibers with the minimum of actual hydration of the cellulose. Such a beater may properly be called a machine to super-calender the individual fibers before they are made into the sheet of paper.

The machine embodying this invention has for its primary object the accomplishment of this flattening effect on the fibers of paper pulp. The ordinary beater works on pulp of relatively thick consistency and works to the best advanta e on such stock.

v The machine of my inventlon is designed to The com The invention consists in the method of treating paper stock, as heretofore out-lined, and in the novel construction and adaptation of a machine consisting essentially of two high-speed solid rolls mounted in a vat of In the drawings, Figure 1 is a plan view of apparatus utilized with an embodiment of my invention. Fig. 2 is a transverse sectional view of the same taken on line 22 of Fig. 1. Fig. 3 is a fragmentary detail. View in horizontal section showing the manmp1 of mounting the bearings of the crushing ro s.

Referrin to said views, the reference numeral 1 indicates a vat of semi-circular form in cross-section having vertical walls 2 and 3 in" which cylindrical rolls 5 and 6 are rotatably mounted, and arranged symmetrically with respect to the interior configuration of the vat. An inlet for the'admission of a mixture of pulp and water is provided at '1 upon one side of said vat and upon the opposite side an outlet 8 arranged below the levelof the inlet is provided with means to adjust the level of said outlet whereby the flow of pulp stock through the vat may I be more efiiciently controlled.

Such means illustrated herewith consist of vertically arranged guideways 10 formed or provided upon the side walls 2 and 3 of the vat, and one or more strips 11 of suitable widths adapted to have their opposite ends engage within said guideways and form a weir or gate over which the stock must flow and the relative heights of the inlet and outlet adjusted.

, 12 indicates a launder or trough through which the pulp-stock is conveyed to the vat and 13asimila-r device to catch the overflow and convey the same to its desired destina tion.

Said rolls 5 and 6 are each provided with axially disposed spindles 21 which are mounted for rotation in journal-boxes 15 and 16, respectively, secured to the end walls 2 and 3. The axes of said rolls are in parallel and preferably arranged in horizontal relation so that the current of liquid carrying the wood fibers to be treated is directed upwardly through the friction of the roll surface in the water;

The perimeters of the rolls are in extremely close proximity, which point of closest proximity may be termed herein, for

convenience, the pinch. The clearance at the pinch is only such as to avoid as much as practicable, actual contact between the rolls although to get the desired flattening effect on fibers, it is essential that the rolls operate with a clearance between the rolls of less extent than the thickness of the individual fibers.

The spindles 21 of the roll 5 are mounted in apertured bearing-blocks 17 within the journal boxes 13- and .a suitable hard rubber or other cushioning device 18 may be inserted therein to lessen the'vibrationqdeveloping from the relatively rapid rotation of the roll.

The spindles 21 of the roll 6 are similarly mounted in bearing-blocks 20 which are slidably secured in journal-boxes 16. A set-screw or equivalent 23 .is threaded through the journal boxes 16 upon the side adjacent the roll 5 and engaging the block 20 to limit the movement of the roll 6 toward the companion roll 5.

A spring 25 engages each of the blocks 20 upon their opposite side, whose tension is regulated by means of set-screws 26. f

It is essential that said rolls be driven at a relatively highspeed, that is to say, about five hundred revolutions per minute in order to develop a sufficient surface film friction with a relatively smooth surfaced roll and to obtain the desired capacity and output.

The rolls are shown independently driven as by power belts Q7 and 28 engaging ulleys 30 and 31, respectively mounted upon the spindles of rolls 5 and 6, but under certain circumstances it may be preferable to provide a direct drive to only one roll and actuate the other b its friction from the driven roll dueto bers that pass therebetween.

One or both of said rolls are provided with a plurality of spaced circumferentlal grooves. Such grooves may be separate ring channels 32 extendin aroundthe c1rcumference of the roll w th the plane of the groove at right angles relative to the axis ofthe roll, as shown in Fig. 1.

The purpose of these grooves upon the rolls is to equalize the conditions atthe artual pinch zone of the rolls to permit of the passage of a certain amount of water-between the rolls to maintain proper consistency of pulp after passing and to assist .in the approach of fiber to the pinch. The rolls are made of any suitable material, for exan'iple, steel, bronze, cast iron or hard rubber, and may be both of the same material or each of different material. A relatively smooth polished surface is desirable, but this may be microscopically rough and relatively so in com arison with the minute dimensions of individual pulp fibers. A doctor is slidably mounted in guideways 37 in the end walls of the vat anden gages with the upper surface of the roll 5, whereby the course of the pulp travels throughthe' vat and relative to the rolls, may be controlled. The ends of the rolls make a close running fit with the ends of the vat. The arrangement and disposition of the rollsin the vat, and the disposition of the doctor 35 relative to the roll, result in certain zones or areas being formed within the vat that may be described as follows:

- The pulp stock is received in zone. A and flows through channel'B owing to .the relatively high hydraulic head usually maintained in said zone, and to the film friction generatedby the rapid revolution of the roll "5 in the direction indicated by the i the pulp through the vat, the larger part of 1 the pulp material being drawn between the rolls and entering the zone D where such inaterial can flow directly out of the-out- A zone E is formed beyond the ,roll 6 which is principally white water from which the pulp has been largely extracted. The rotation of the roll16 in the direction indicated by the arrow prevents tda large extent the free movement of the water through the constricted passage F. v

The rolls 5 and 6 being rapidly rotated in the directions indicated by the respective arrows in Fig. 2, cause an upward move: ment or current of water and pulp through their points of closest proximity. or pinch. On even a highly polished roll running at the speed indlcated, there is athin friction zone at the surface which will carry pulp and water up to'the pinch. ,Even though this zone be-ve of the roll, together with its length, is ample to assure all the water and pulp in even dilute stock being carried to the pinch.

thin the surface velocity v This swirlfis effective in tending to bring all fibers into this thin friction zone on the surface of the rolls and thereby assist in their being caught at the pinch of the rolls. This swirl will maintain a natural battle to the progress of this pulp toward theoutlet 8 b the assage F and will increase the ten ency or it to be caught between 'the' rolls before it can escape under the rolls 6 and thence out of the vat. The grooves 33 in one or, both rolls will effect a slight upward current, pulling "the fibers into the ,pinch zone.

The speed at which the rolls can be run. together with the permissible and practical length of such rolls, gives a large capacity to a machineof this designeven withthe small clearance between rolls necessary to effect a flattening of the individual. fibers.

rolls, uniting the pulp and water in the vat at the side opposite to said inlet, and discharging the pump and water from saidvat.

2. In apparatus of the class described, a vat, a pair of cylindrical crushing rolls rotatably mounted in said vat and arranged to have their peripheral surfaces spaced apart, and means to admit and maintain a continu- -ous flow of pulp and Water within said vat at adjusted heights whereby said rolls are submerged with their two axes in a common horizontal plane.

3. In apparatus of the class described a vat adapted to contain paper pulp and water of dilute consistency, cooperating rolls rotatably mounted in said -vat,'narrow annular grooves in the periphery of saidr'olls, means to rotate said rolls in opposite directions whereby their surfaces at their closest proximity move in upward directions, said rolls being slightly spaced apart to admit of the passage of pulp fibers therebetweem '4. In apparatus of the class described, a

- vat adapted to contain paper-pulp and water, a pair of cooperating rolls rotatably mounted in said vat, means to rotate said rolls in opposite directions whereby their surfaces at theirclosest proximity travel in upward directions, said rolls being suitably spaced apart to admit of the passage of pulp therebetween, and a circumferential groove formed upon the surface of one of said rolls for the passage ofpulp and water.

5. In apparatus of the class described, a vat having an inlet at one side thereof and an outlet at the opposite side of said vat,-

means to adjust the relative elevation of said A inlet and outlet to control the flow of pulp and water through the vat, a pair of rolls rotatably mounted in the end walls of saidv vat, and means to adjust the clearance be-- tween said rolls.

'6. In apparatus of the class described, a vat having an inlet at one side thereof and an outlet at the opposite side of said vat, means to adjust the relative elevation of said p inlet-and outlet to control the flowof pulp and water through the vat, a pair of rolls rotatably mounted in the end walls of said, vat, means to adjust the clearance between said rolls, and grooves formed upon the face of said rolls.

7. In apparatus of the class described, a vat having vertical substantially semi-circular end walls and bottom and side walls of semi-circular configuration in cross-section, said vat havlng an inlet upon one side and ed in said vat, one of said rolls having on nular grooves formed in its periphery affording a passage between said rolls for said pulp material.

9. In apparatus of the class described. a

vat, said 'vat having an inlet upon one side and an outlet at its opposite side, said outlet beingat a lower elevation than said inlet, and a pair of rolls having their axially arranged spindles rotatably mounted in the end-walls of said vat, the axes of said rolls being in a substantially horizontal plane and at rightangles to the flow of liquid material through said vat, and a doctor associated With the roll adjacent said inlet whereby the course of said material toward said outlet is beneath said rolls.

10. In apparatus of the class described. a

vat having an inlet onone side and an ,outlet on the opposite side thereof, a air of cooperating submerged rolls rotatablymounted in said vat, and adoctor in close proximity to the 'top' of one of said rolls-to cause material that enters said vat to pass beneath said rolls before it reaches the outlet.

.11. In apparatus of the class described, a vat having an inlet and an outlet upon opposite sides, said outlet being adjustable in height to vary the rate of flow of pulp material through the vat, a pair of rolls rotatably mounted'in said vat and adapted to be independently rotated, said rolls having their axes in parallel and in a plane intermediate the vertical and the horizontal whereby the material passing therebetween is upwardly directed.

12. In apparatus of the class described, a

' vat, said vat having an inlet upon one side and an outlet at its opposite side, said outlet being at a lower elevation than said inlet, a air of rolls, the axes of said rolls being in a substantially horizontal plane and at right angles to the flow of liquid material through said vat, and a doctor associated with the roll adjacent said inlet whereby the course of said material toward said outlet is beneath said rolls. Dated this 2nd day of May, 1917.

GUY C. HOWARD. 

